The Little-Known (But Not Uncommon) SSc-Lupus Overlap Syndrome

Not So Uncommon

Dr. Johnson

The study’s estimated SSc-SLE overlap syndrome prevalence of 6.8% suggests the condition is not uncommon in SSc, the co-authors write. It may be a conservative estimate, because all patients included in the study were required to fulfill the classification criteria for both diseases. Cases of mild or early, physician-diagnosed disease that did not fulfill all the criteria may have been missed, they write.^11,12

More research on the specific characteristics of SSc-SLE overlap syndrome will help rheumatologists more accurately classify these patients, says Dr. Johnson.

“As long as our understanding of this group of patients evolves, our ability to identify them early will continue to improve,” she says. “The new classification criteria for SLE being developed with the support of ACR and EULAR may assist with the earlier classification of people with SLE. The ACR/EULAR classification criteria for SSc has been shown to classify those with SSc earlier.”

Survival bias may have affected the study’s results, because some SSc patients may have died before they developed SLE, the co-authors write. On the flip side, SLE characteristics may bring a patient’s SSc diagnosis to light earlier, a possibility noted by the younger age and less frequent sclerodactyly seen in the overlap group. The co-authors also note that the small proportion of overlap patients with SSc antibodies may be low, because measurement of these antibodies was not readily available in the early years of the study period.

This large, well-characterized study, with its robust mortality data, is an important way to provide new insights and potential guidance for clinicians who encounter patients with suspected SSc-SLE overlap, says Dr. Johnson.

“SSc-SLE overlap subjects less frequently have cutaneous manifestations of SSc, [but] clinicians should still screen for serious internal manifestations, notably interstitial lung disease, pulmonary arterial hyper­tension and scleroderma renal crisis. [Enthusiasm for] these findings should be tempered; they require external validation,” she says.

Based on their study’s findings, the co-authors conclude SSc-SLE overlap syndrome patients are typically female and younger at diagnosis, and less frequently feature cutaneous SSc manifestations. They recommend rheumatologists regularly monitor overlap syndrome patients for serious SSc complications, such as PAH, ILD, renal crisis and digital ulcers.

Susan Bernstein is a freelance medical journalist based in Atlanta.

References

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